The KLM-Shell LabelsWilliam B. JensenIn response to a reader's inquiry, this column traces the origins of the K, L, M labels for the shells of the Bohr atom.Jensen, William B. J. Chem. Educ.2003, 80, 996.

Have Orbitals Really Been Observed?Eric R. ScerriRecent reports claiming to have observed textbook d orbitals are analyzed and it is argued that what was observed indirectly, and not for the first time, was actually electron density. It is also suggested that the tendency to use the terms electron density and orbital to mean the same thing will give rise to confusion in chemical education. Scerri, Eric R. J. Chem. Educ.2000, 77, 1492.

Computational Chemistry |

MO Theory |

Quantum Chemistry |

Theoretical Chemistry

Ionization Energies, Parallel Spins, and the Stability of Half-Filled ShellsPeter CannThree methods for explaining the decrease in first ionization energies between group V and group VI elements are described and commented upon. The quantum mechanical origin of the unhelpful concept of half-shell stability is explained in terms of exchange energy, for which the alternative term parallel spin avoidance factor is suggested. It is recommended that for pre-university students the simplest explanation, in terms of Coulombic repulsion between two electrons occupying the same orbital, is adopted: it involves fewer difficult concepts than the other explanations and its predictions are no less accurate. Cann, Peter. J. Chem. Educ.2000, 77, 1056.

Atomic Properties / Structure |

Periodicity / Periodic Table |

Quantum Chemistry |

Theoretical Chemistry

The Genius of Slater's RulesJames L. ReedWith only a few modifications a procedure has been developed that yields the one-electron energies for atoms and ions with a level of detail very well suited for instruction in the structure and properties of atoms. It provides for the computation of very reasonable values for such properties as ionization energies, electron affinities, promotion energies, electronic transitions, and even XPS and ESCA spectra. Reed, James L. J. Chem. Educ.1999, 76, 802.

Atomic Properties / Structure |

Quantum Chemistry |

Theoretical Chemistry |

Spectroscopy

How Good Is the Quantum Mechanical Explanation of the Periodic System?Eric R. ScerriThe use of quantum mechanics, or more specifically, orbitals and electronic configurations in teaching general chemistry is now such a widespread trend that it would be utterly futile to try to reverse it. Moreover, orbitals and configurations have been extremely useful in providing a theoretical framework for the unification of a multitude of chemical facts. Scerri, Eric R. J. Chem. Educ.1998, 75, 1384.

Periodicity / Periodic Table |

Quantum Chemistry |

Theoretical Chemistry

Deducing the Shell Model from Ionization Energies and the Use of Models in Introductory ChemistryRonald J. Gillespie, Richard S. Moog, and James N. SpencerA major objection of Rioux and DeKock is the statement in the authors' earlier paper that electron repulsion is responsible for the relative ionization energies of H and He. The commentators work clearly shows that a quantum mechanical treatment of this problem reveals that kinetic energy considerations play a crucial role in these values. However, although their criticism is appropriate in the context of this more sophisticated QM treatment, it does not in any way invalidate the authors original paper, the goal of which was to provide a model, namely the shell model, for the electronic structure of atoms that is consistent with experimental ionization energies.Gillespie, Ronald J.; Moog, Richard S.; Spencer, James N. J. Chem. Educ.1998, 75, 539.

Atomic Properties / Structure |

Quantum Chemistry |

Theoretical Chemistry

In Defense of Quantum NumbersRobert M. RichmanA recent paper has argued that the derivation of the periodic table using quantum numbers is a topic that should be eliminated from introductory chemistry courses because it is too abstract, mysterious, and esoteric. A rebuttal is offered based on the claim that it would be wrong to omit discussions of the inductive approach of Mendeleev and the deductive approach initiated by Schroedinger, because they compose the consummate example of that interaction of empirical and rational epistemologies that defines how chemists think. Richman, Robert M. J. Chem. Educ.1998, 75, 536.

Pictorial analogies VII: Quantum numbers and orbitals Fortman, John J.Quantum number n is related to the size of a house, l is related to the shape of a house, and m is compared to the direction the house is facing. Pictures are included.Fortman, John J. J. Chem. Educ.1993, 70, 649.

Understanding electron configurations Rieck, David F.The author has successfully employed an analogy for understanding electron configurations recommended for use in secondary schools as well as in nonmajor sections of college general chemistry.Rieck, David F. J. Chem. Educ.1990, 67, 398.

Atomic Properties / Structure |

Nonmajor Courses

Visualization of electron clouds in atoms and moleculesDouglas, John E.110. Visualization of the electron orbital concept continues to challenge and intrigue chemical educators. [October and November 1989 Computer Series both inadvertently called number 107. Numbering restored by skipping 109 and calling January 1990 number 110.]Douglas, John E. J. Chem. Educ.1990, 67, 42.

Atomic Properties / Structure |

Molecular Properties / Structure

Teaching the shapes of the hydrogenlike and hybrid atomic orbitalsAllendoerfer, Robert D.The purpose of this article to show that, in this age of computer graphics, the "difficult to obtain" argument no longer has merit and to give an example of where the standard treatment gives insufficient attention to detail in describing the nodal surfaces of hybrid orbitals.Allendoerfer, Robert D. J. Chem. Educ.1990, 67, 37.

The electronic periodic chart of the elementsvon Marttens Osorio, Hernan; Goldschmidt, AlfonsoA scheme for the arrangement of the elements that allows students to understand and write down the electronic configuration of any given element.von Marttens Osorio, Hernan; Goldschmidt, Alfonso J. Chem. Educ.1989, 66, 758.

Periodicity / Periodic Table |

Atomic Properties / Structure

Another quantum number?Perrino, Charles T.; Peterson, Donald L.The presentation of the concept of "spin" in many textbooks is inconsistent, misleading, and in some cases even incorrect.Perrino, Charles T.; Peterson, Donald L. J. Chem. Educ.1989, 66, 623.

Updating the atomic theory in general chemistryWhitman, MarkPresents a descriptive overview of the recent achievements that have furthered the understanding of atomic structure to provide instructors with the background necessary to enhance their classroom presentations.Whitman, Mark J. Chem. Educ.1984, 61, 952.

Using the Aufbau principle Whitmer, John C.This question is written with the belief that general chemistry students should not only attain an understanding of the Aufbau principle enabling them to write down electron configurations, they ought also recognize the correspondence between the quantum numbers and the structures of the periodic table.Whitmer, John C. J. Chem. Educ.1978, 55, 515.

The five equivalent d orbitalsPowell, Richard E.Several textbooks assert that there is no way of choosing the five d orbitals so they have the same shape but differ only in their orientation.Powell, Richard E. J. Chem. Educ.1968, 45, 45.

Atomic orbitals: Limitations and variationsCohen, Irwin; Bustard, ThomasThe three most widely used methods of arriving at a set of atomic orbitals afford respective hydrogen-like orbitals, self-consistent field orbitals, and various analytical approximations such as the Slater or Morse orbitals, all of which may differ greatly in shape and size from each other.Cohen, Irwin; Bustard, Thomas J. Chem. Educ.1966, 43, 187.

A periodic table and new periodic functionsSzabo, Z. G.; Lakatos, B.A theoretically correct yet simple periodic system may be obtained by rearranging the long periodic table in such a way that the inert gases are situated in the middle.Szabo, Z. G.; Lakatos, B. J. Chem. Educ.1957, 34, 429.